Zinc-iodine battery breakthrough: 60,000+ charge cycles, full charge in 3 minutes

Researchers at Flinders University, Australia, appear to have solved one of the most persistent obstacles facing aqueous zinc-iodine batteries: their short operational lifespan. Publishing their findings in Angewandte Chemie, the research team reportedly developed a battery that can withstand more than 60,000 charge-discharge cycles while fully recharging in as little as three minutes. Depending on the operating settings, the cells run at 1.3 to 1.4 volts and deliver either 200 mAh/g across 8,000 cycles with a seven-minute charge, or a reduced 150 mAh/g across the much larger 60,000-cycle figure. The degradation rate is reported to be as low as 0.0001% to 0.0003% per cycle.

Aqueous zinc-iodine batteries previously suffered from the "shuttle effect," in which polyiodine compounds escape through the battery's separator and steadily erode performance. To address this problem, the researchers built a cage-like structure from cyclodextrin, an inexpensive, starch-derived polymer commonly found in food and cosmetics whose water-attracting outer layer and water-repelling interior trap and release the problematic polyiodides on demand.

Beyond the technical fix, zinc-based batteries are a much safer, more affordable, and more readily available alternative to lithium-ion technology. They largely remove the fire hazards associated with lithium chemistries, while matching or even surpassing lithium-ion in terms of both specific energy and energy density.

Furthermore, Australia holds 20-28% of the world's known zinc reserves, which presents an opportunity that could potentially counter China's monopoly over the lithum-ion supply chains and address the problem of environmental waste. Australia produces around 3,300 tonnes of lithium battery waste each year, which is expected to surge to over 136,000 tonnes by 2036.

For now, the technology remains at the prototyping stage rather than commercial rollout. The Flinders lab says it is partnering with industry to build a prototyping platform. Whether this translates into an actual domestic industry, however, depends on factors well beyond battery chemistry, including manufacturing investment and market adoption, neither of which the research addresses.